1. Field of the Invention
The present invention relates to a brake master cylinder, and more particularly to a brake master cylinder that controls switching on a brake lamp using a Hall sensor and a magnet that is installed in the master cylinder.
2. Description of the Prior Art
In general, the master cylinder of a vehicle's brake refers to an apparatus for receiving a force that is applied as a boosting force from a pressure difference between the vacuum and the atmosphere from a booster, converting the force into a hydraulic pressure, and transmitting the hydraulic pressure to a cylinder to generate a braking force.
The brake master cylinder is provided with a unit for detecting an operation of a piston as a result of a pedal effort to switch on or off the brake lamp. As an example, Korean Patent Application Publication No. 10-2009-0101566 and Korean Patent No. 10-1085801 disclose master cylinders that switch on a brake lamp using a Hall sensor.
A conventional brake master cylinder includes a ring-shaped magnet installed in a piston that is slid and moved by a pedal effort, and a Hall sensor that is installed in a cylinder body of the master cylinder at a location corresponding to the magnet such that the piston may be moved forwards and rearwards in the cylinder body. The Hall sensor detects the strength of a magnetic force that due to the movement of the magnet that is installed in the piston to switch on the brake lamp.
Generally, the ring-shaped magnet installed in the piston has a high magnetic flux density, and a rare earth magnet formed, for example, of neodymium and samarium, which can be easily miniaturized is used as the ring-shaped magnet. However, in recent years, due to the sudden rise of the price of rare earth, the price of the rare earth magnet that is formed of the rare earth also has risen and thus the development of a replaceable technology is urgent. In particular, in order to use a general magnet instead of a rare earth magnet, the volume of the magnet should become larger in order to increase magnetic flux density, and because the interior of the master cylinder is a limited space, it is difficult to replace the rare earth magnet with a general magnet.